Abstract: The invention provides methods for the diagnosis and treatment of musculoskeletal disorders relating to the Hedgehog pathway, including but not limited to muscular dystrophy (e.g., Duchenne Muscular Dystrophy) using agents that agonize Sonic Hedgehog (shh), and thereby, the Hedgehog signaling pathway. Said agonizing agents include, e.g., the compounds of the invention (e.g., a compound of Formula I). The invention also provides methods of screening for agents that are capable of increasing the proliferation of muscle and/or muscle precursor cells.